Ebert notes that the plotline of Brother Bear was originally meant to be inspired by King Lear, although not much of that original inspiration seems to have survived. Bearing in mind (sorry) that The Lion King was clearly rooted in Hamlet, it appears that we've stumbled across an active Disney strategy for finding new stories. Not sure if there's anything like this in the pipeline, but I'd love to see a version of Macbeth among the rabbits.